Lubricant



Patented .iune'so, 1942 1 same : LUBRICANT Bert B. Hncoln, Gordon D.Byrkit, and Waldo L. Steiner, Ponca City, Okla, asaignon, by memeassignments, to Socony-Vacunm Oil Company, New York, N. Y., acorporation of cw or No Drawing. Application April 17, 1940,

g Serial No. 330,084

e Gains. (01. 252-35) Our invention relates to improved lubricants andmore particularly to lubricants containing in combination an additionagent, giving the fin. ished composition increased resistance tooxidation and the formation of corrosive products as well as otherimproved characteristics.

This is a continuation-in-part of our co-pending application, Serial No.223,070, filed August 4, i938.

. Modern mechanical devices require lubricating oils of high filmstrength, high oiliness characteristics, and oxidation-resistingcharacteristics. Straight hydrocarbon lubricants including high quality,highly refined hydrocarbon oils are deficient in these three importantcharacteristics. Oiliness properties, film strength, and resistance tooxidation are of vital importance under con ditions of boundary or thinmm lubrication in" which the lubricating film has been squeezed beetween two moving surfaces by pressure. The importance of these threecharacteristics is magnified with large bearing surfaces and slowspeeds.

Itwillbecleartothoseskilledinthe artthat the viscosity of a lubricantplays no part in these characteristics. A high-quality paraiiin basePennsylvania lubricating oil would still fail if deficient in filmstrength as a rupture of the film would permit metal-to-metal contactand resulting injm-y or seizure. The oil film, lacking in oilinessqualities, imparts resistance to movement. In many conditions of use,the oil must resist oxidation from atmospheric oxygen.

The present-day trend in internal comcustion engines to high compressionratios requires the use of higher film strength lubricants, and'it'hasbeen found that even the best qualityhydrocarbonoilpossessesafilmstrengthtoolowtoenable it to lubricatesatisfactorily.

Many mechanical devices operate frequently under conditions of boundaryor thin film lubrication. Under these conditions, the oiliness, the

film strength, and the resistance to oxidation become most important.

The oxidation of lubricating oil hydrocarbons results in the formationof compounds which polymerize or sludge. Acids are formed which areespecially deleterious under conditions of thin film lubrication. Theacid, too, has an especially adverse effect on modern bearingcompositicns such as cadmium-silver and copper-lead.

. The sludge formed has no lubricating properties,

and even the best hydrocarbon lubricant will be quickly deteriorated ifsubjected to oxidation conditions.

In those devices in which a lubricant is circulated by means of a pump,there is usually a short period when the devices started from acondition of rest in which the surfaces operate under conditions ofsubstantially dry friction, if ordinary hydrocarbon lubricants are used.It will be readily apparent to those skilled in the art that with dryfriction the wear on the friction surfaces is extreme. This condition ismagnified during cold weather when the viscosity of the lubricant ishigh and the oil circulation is slow. An accident to the oil circulationsystem invariably spells disaster with ordinary hydrocarbon lubricants.

In the prior art, it has been the practice to refine an oil thoroughlyby means of acid or selective solvent treatments. This drastic refininghas been necessary in order to remove unstable compounds which willpolymerize or sludge. The refined oil, however, appears to be morereadily oxidizable'than an unrefined oil, with the result that a highlyrefined oil will quickly oxidize and form soluble acids and othercorrosive materials. Highly refined oils, upon oxidation, also formlacquer-like polymers which tend to cause sticking of the piston rings.This sticking in an internal combustion engine results in loss of power,failure of lubrication, scratching, scoring, overheating, and eventuallyfailure of parts, necessitating replacement. It is practicallyimpossible to refine a lubricant in such a manner as to avoid all threeof these difliculties,

namely, slugs, soluble corrosive products, and lacquer.

' The trend of development in internal combustion engines has imposedincreasing burdens upon the oils used for theirlubrication,-particularly with respect to operating temperatures andpressures. At present, the Diesel type of.

engine probably represents extreme requirements in both of theserespects; but it is not alone in the imposition of severe burdens uponthe lubricating oil used. The useful operating life of a lubricatingoil, in such service, is determined, in large measure, by its thermalstability and by its physical cflpacity to continue functioning as alubricant, at the high temperatures and high pressures encountered. Onemeasure of thermal stability is resistance to oxidation, and theconsequent tendency to. form sludge; but in another aspect the efi'ectof thermal instability is determined not only by the extent of oxidationor decomposition but also by the character of the products of suchdecomposition or oxidation and by the extent and location, within theengine, of deposits of such products.

cants, which In the Diesel typ tures to which the particularly at thetop nounced with respect to sequent sticking oi the rings rapidlydeprives the piston and cylinder wall or proper lubrication, inducingwear and, irequently, scoring the cylinder wall. The iormation oisuch"carbon hard enough and coherent enough to involve sticking oi therings, is materially retarded. ii not avoided, by the use oi theimproved lubricating oil compositions oi our invention; and in thisaspect the self-cleaning properties oi the lubricating oil compositionsoi our invention, with respect to the engine, make a mere change oi oila substitute, economicai with respect both to loss oi service time andcost, ior many otherwise necessary cleaning and repair Jobs.

One object oi our lubricant which has reacting with metal surfaces,penetrating or being adsorbed on the metal surfaces in order to leave atall times a film of lubricant of high oiliness character which willremain on the metal surfaces irrespective of the length oi time themachine or' device has been idle.

Another object of our invention invention is to provide a is to providea lubricant oi high oiliness properties so that the lubricating filmoperation.

Another object oi our a hydrocarbon lubricant I with unburned fuel orwith other light hydrocarbons, reducing the viscosity, will neverthelesshave such a degree oi oiliness as to offset the dilution withoutimpairing the load-carrying ability of the lubricant.

Another object oi our invention is to provide a lubricant which iseilective in highly refined, poorly refined, or even wholly unrefinedlubriwill provide the finished composition with marked anti-sludging.increased film strength, and high oiliness characteristics.

Another object oi our invention'is to provide lubricants containingadded materials which reduce markedly the lacquer and carbon-formingtendencies of the hydrocarbon portion of the lubricant and difllcultiesdue to ringsticking,

Other and will give a very smooth and even iurther objects of ourinvention will appear from the iollowing description.

In general, our invention contemplates the coniection oi a lubricantcontainingan oil oi lubricating viscosity and an addition agentcomprising stannic tin salts or soaps oi organic acids containing atleast one aromatic nucleus. The hydrocarbon oil, if desired, may be oiiuel hydrocarbon oil so that, upon combustion oithe iuel, the depositionoi the addition agent upon the cylinder walls will result in itsbecoming admixed with the orankcase lubricant.

.By way oi illustration and not by way oi limitation, some of theparticular stannic salts of organic acids containing atleast onearomatic nucleus will be mentioned hereinbelow. The aromatic nucleus isessential to provide suiilcient stability andsolubilitv in hydrocarbons.Tin stearate. ior example; is'not suitable the important property ofinvention is to provide which, when diluted oi our invention. It isdiihcultly soluble in hydrocarbon oils. Iin naphthenate is anotherexample of a compound not falling within the class 0! the compounds ofour invention. It is, compared with our compounds, unstable and does'ing the compounds.

and 1mm strength in the use drous stannic I. Acid group on aromatic rinA. Alkylated aromatic acids 1. Stannic p-cetyl benzoate (ClOHBCBHACOa)4Sn 2. Stannic tri-isohexylbenzene sulfonate ((CsHn) sCsHzSOa) 4Sn B.Aldehyde acids 1. Stannic salt of terephthalic acid (H.CO.CsH4COr)4Sn C.Keto acids 1. Stannic benzophenone-i-carboxylate (CsHsCQCshhCOz) 4Sn 2.Stannic p-lauroylbenzoate (CIIH23CO.C6H4CO2) 4511 D. Ether acids 1.Stannic p-amyloxybenzoate (CBHllOCdHiCOZ) 4Sn 2. Stannicp-phenoxybenzoate (CeHsOCeI-hCOz) 4Sn E. Nitro acids 1. Stannicl=nitronaphthalene 2 carboxylate (CioH6(NO2) C02) 4511 F. Amino acids 1.Stannic p-diamylaminobenzoate ((CsHii) zNCcHcCOa) 4Sn 2. Stannicchloro-diethylaminobenzoate (CaHs) aNCsHaCLCOz) 4S1). II. Acid group onside chain A. No substituents on aromatic radical 1 Stannicphenylstearate (CmHsdCcHs) C02) 4Sn B. Alkylated on aromatic radical 1.Stannic tributylphenylacetate ((C4Hc) :CcHaCI-IaCOs) 4Sn 2. Stannictetrabutylcinnamate ((C4Ho) 4CcH.CH=CHCO2) 451i 3. Stannictridodecylhydrocinnamate ('CuHzs) :CcHaCHaCHaCOz) 4Sn 4. Stannicdelta-tributylphenyl-n-valerate ((Cd-ls) :CsHziCHz) 4CO2) 481i 5.Stannic di-isohexylphenylethyl sulionate ((CsHn) :CsHsCH-zCmSOs) 4Sn C.Keto acids 1. Stannic-o-butyrcphenylacetate (CsHrCQCsHiCHiCOi) 4Sn D.Ether acids 1. Stage beta-ethoxyethylphenylace- (CzHsOCHzCHaCeI-LCHzCOz)4Sn 2. Stannic beta-chloroethoxypheny'lacetate (ClCHrCHaOCcHaCHzCOzhSnThe preparation of some oi the acids useful in making these stannicsalts is described in U. S. Patent 2,111,820 to Steindorfl et al. Thestannic salts are made, for example, by treating dilute methanolsolutions oi the sodium or ammonium salt oi the acid with a methanolsolution oi anhychloride. (CnCh) and filtering oi! the half aldehyde of2,288,289 the soap. It may also be separated from the" methanol solutionby dissolving in a light oil (70 or 150 pale oil). The soap or its oilsolution is freed from moisture and methanol by warming under reducedpressure.

Any of the foregoing compounds or other members of the classesrepresented by them or derivatives of these compounds are within thescope of our invention.

It is to be understood that in practicing our invention, oil-solublestannic salts of the type described are to be selected. Some oftheexeven five per cent or more. Form 0.01 per cent to 1.5 per cent ofmost of the compounds is usually considered adequate.

Furthermore, it is well known that different types of oils havediiferent capabilities of dissolving a given material. For somepurposes, therefore, we prefer paraflinic lubricants; for otherpurposes, asphaltic lubricants{ and for still other purposes, naphthenicor mixed base lubricants. Another method of obtaining a satisfactorymixture of addition agent with the hydrocarbon 011 is the use of amutual solvent to bring the addend into solution. Alternatively,peptizing agents may be added to maintain thestannic salts in permanentsuspension.

Many of the more diiiicultly soluble materials are rendered more solubleby the introduction of alkyl groups, particularly those containing fouror more carbon atoms. The isoamyl, cetyl, lauryl, and octadecyl radicalsand radicals from paraifin wax greatly increase the solubility oforganic compounds in oil. One or more of such groups may be introducedinto any of the foregoing compounds, derivatives, or homologues, asrequired. For example, stannic stearate is not very soluble inhydrocarbon lubricating oils, but stannic phenylstearate is much moresoluble; and stannic phenylstearate with a wax radical on the phenylgroup is still more soluble.

The selection of a particular compound or compounds to be used as anaddition agent to the hydrocarbon oil is to be made considering thephysical and chemical properties of the various compounds and the use towhich the blend is put.

By oil having lubricating characteristics in'the appended claims, wemean to include the socalled mineral oils and various hydrogenated,polymerized, and otherwise synthetically treated oils such as voltolizedoils, aluminum chloride treated oils, and the like. Furthermore, thelubricating oil may consist in whole or in part of shale oil or ofanimal or vegetable oils such as caster oil, lard oil, corn oil,cottonseed oil, and the like.

It is sometimes advantageous to combine more than one of these compoundsin a blend to obtain particular properties. We accomplish this by mixingtwo or more of these compounds together and blending the mixture withthe hydrocarbon oil or by blending one in the hydrocarbon oil,

blending the second into this mixture, and so on the film strength. andoxidation characteristics of the hydrocarbon oil. For example, thesludging tendencies may be decreased by as little as 0.001 per cent ofour tin compounds. The oxidation characteristics of lubricants are veryim' portant, and these are markedly improved by our compounds.' Theability to reduce friction is another feature contributed to lubricantsby some of our tin compounds.

Itmay be desirable to include in one and the same blend, in addition tothe addends here described, other addends for'speciflc purposes. Thus wemay add a pour point depressor such as naphthalenechlor wax condensationproduct, a viscosity index improver such as certain resins orpolymerized hydrocarbons and sulfur or phos- 'phorus-containinginhibitors, in addition to our tin compounds. Furthermore, various othermetallic compounds may be added to the blend without interfering withthe action of our ingredients. Indeed, in some cases it is advantageousto combine with our tin compounds in a hydrocarbon oil blend suchmaterials as calcium dichlorstearate, chromium olate, aluminum stearate,and other metallic soaps. Various halogenated oxygen-bearing ring 'oraliphatic compounds may be added.

Our addends are admirably suited for use in lubricating oils of alltypes, including those designed for use in automotive crankcases, Dieseloils, and any other oils of lubricating viscosity. Furthermore, ouraddends are advantageously blended in gasoline and other petroleum fuelseither directly or after being blended first in a lubricating oil andthen added to the fuel. Soap-thickened lubricants of all types rangingfrom those showing only a slight increase in viscosity over that of themineral oil alone to the semisolid and solid greases containing fiftyper cent or more of soap are amenable to treatment according to ourinvention. The ordinary soaps used in making greases may be replaced inwhole or in only small part by some of our tin compounds. We may use upto 30 or 40 per cent of our tin compounds. These addends modifyconsiderably the tackiness, penetration, resistance to breakdown byworking or heat, and other properties of the greases. In making thesegreases, the usual soaps such as sodium stearate, aluminum stearate,calcium soaps of beta fat, and the like may be used to form the largepart of the necessary soap. Various other thickening ingredients ormaterials for other purposes may be added. These include yarn, hair,graphite, glycerol, water, lampblack, mica, zinc dust, litharge, and thelike.

The following examples of blends of our addends are given asillustrations and not as limitations: 1

Example 1 Per cent Mid-Continent paraflin base S. A. E. 30 99.0

Example 4 a Per cent Parafiin base bright stock-.. 58.0 Paraflin baseneutral oi1..' 40.0

Sulfurized methyl estersof corn oil fatty sir-ids v Stannicp-1auroylbenzoate 0.2 Calcium dichlorostearate 1.3 Diphenyl-chlorwaxcondensation product 0.4

Mid-Continent paramn base S. A. E. 40 93.8

Voltolized corn oil 5.0 Chlorodiphenylene oxide 1.0 Staxmicphenylstearate 0.2

It will be obvious that we prefer the stannic of the tin salts asaddends to lubricants. In general the stannic salts are more soluble inhydrocarbon oils than the stannous salts. It has even been suggestedthat some of the acids represented in these salts be added to the blendsof the stannous salts to increase the solubility of the salts; howeverwe prefer to avoid the use of free acids because of their corrosiveaction on certain metal parts being lubricated, especially copper-leadand cadmium-silver bearings. The free acid is not necessary with thestannic salts. We believe the stannic salts are more soluble inhydrocarbon oils due to the higher content or organic radicals in thesalt. We have also found that the stannic salts are more efour claims.It is further obvious that various changes may be made in details withinthe-scope of our claims without departing from the spirit of ourinvention. It is therefore to be understood that our invention is not tobe limited to the details described.

Having thus. described our invention, we claim:

1. A lubricant comprising a major proportion of an oil of lubricatingviscosity and a minor proportion of a stannic salt of an organic acidbearing at least one aromatic ring.

2. A lubricant comprising a major proportion of an oil of lubricatingviscosity and a minor proportion of a stannic salt of an organic acidcontaining both aromatic and aliphatic radicals.

3. A lubricant comprising an oil of lubricating viscosity and from 0.001to 5 per cent of a stannic salt of an organic acid hearing at least onearomatic ring.

4. A lubricant comprising a major proportion of an oil of lubricatingviscosity and a minor proportion of stannic phenylstearate.

5. A lubricant comprising a major proportionof an oil of lubricatingviscosity and a minor proportion of stannic p-lauroylbenzoate.

6. A lubricant comprising a major proportion of an oil of lubricatingviscosity and a minor proportion of stannic tributylphenylacetate.

BERT H. LINCOLN. GORDON D. BYRKIT. WALDO L. STEINER.

' CERTIFICATE 70F coizREc'n ON.

Patent No. 2,2 8,289. June 0 191mg BERT H.'LINCOLN, ET AL.'

It is hereby certifieddiqat error appears in the printed specificationof the above nunbered patent requiring correction as follows: Page 1,second column, line 52, for "slugs" read -sludge-; page 2, secondcolumn,-

line 65, for that portion of the formula readingf'CH read "CH andthat-the said Letters Patent should be read with this correction thereinthat the same may conform to the record of the case in the PatentOffice.

Signed and sealed this 15th day of October, A. D. 19L 2.

v Henry Van Arsdale, (Seal) Acting Commissioner of Patents.

